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Straight ahead on "Our World" ... Fossils of evolution's 'Missing link' ... a new bid to solve Africa's soil crisis ... and what patients around the world like — and don't like — about their national health systems...

BERWICK: "The fundamental conclusion from this report is that the U.S. is far from the best-performing health care system in the world, even though it's by far the most expensive"

Scientists have discovered fossils in northern Canada of a 375-million-year-old fish that they say is the missing link between fishes that swim in the sea and four-legged animals that walk on land.

The three fossils are good-sized specimens — the largest is 2.7 meters long. And the researchers says tiktaalik, as the creature has been named, represents an important transitional point in evolutionary progress.

Neil Shubin of the University of Chicago is one of the co-authors of a paper announcing the discovery just published in the science journal "Nature."

SHUBIN: "The discovery's really important because it's the discovery of a new kind of fish that blurs the distinction between fish and land-living animals. It has a mosaic of features seen in both. Like a fish, it has scales and fins and a very primitive jaw. But like a land-living animal, it has ribs that fit together. It has a neck where the head can move around separately. And importantly, when you look inside the fin, it has a number of bones that compare very closely to the bones in our own wrist, in our own hand."

The fish had a flat skull, like a crocodile, and Shubin said in a "Nature" podcast that tiktaalik occupies a middle position in a series of ancient creatures that, together, paint a picture of animal evolution from swimming to walking. Shubin noted that Tiktaalik isn't so much the single missing link, as one of a series of steps from water to land.

SHUBIN: "When you put this whole series together, it's truly one of the remarkable transitional series between different kinds of life in the history of the Earth."

Although the fossils were found in the Canadian arctic, the area during the Devonian period, 375 million years ago, was in the tropics, not far from the equator.

From ancient fossils to modern medicine now.

U.S. doctors have successfully implanted human bladders grown in the laboratory into patients with bladder disease. These custom bladders were grown from the patients' own cells on a specially shaped mold. VOA's David McAlary reports that the surgeons hope to use the technique to repair or replace other internal organs.

McALARY: Seven youths aged four to 19 are the first beneficiaries of new bladders engineered by Dr. Anthony Atala and colleagues at Wake Forest University in North Carolina.

ATALA: "In terms of actually engineering a complex construct that we engineer outside the body and then we implant inside the body, this is really the first time we have been able to do that."

McALARY: The youthful patients Dr. Atala treated had congenital bladder disease that caused unnaturally high pressures inside the organ. This problem can damage the kidney, which produces the urine passed by the bladder.

Traditional bladder reconstruction usually involves grafts from the small intestine or stomach. But the use of such tissue can cause complications because it is different from bladder tissue. Intestinal or stomach tissue absorbs liquids, while the bladder is designed to excrete them.

Atala's team took an alternative approach. They extracted bladder tissue from the seven young patients, and used it to grow muscle cells and bladder cells in the laboratory. They placed the cells layer by layer on bladder-shaped molds made from collagen, the main protein of connective tissue.

ATALA: "This is done very much like baking a layer cake, if you will. After the mold is fully seeded, you are putting this into this incubator, which is like the oven. Seven weeks from the time you actually start with the small piece of tissue from the patient, it is ready to be implanted back into the patient."

McALARY: The Wake Forest University team reports in the journal "Lancet" that the engineered bladders were durable and functional through five years of follow-up without any off the ill effects associated with the older technique using bowel tissue. Since the organs are made from patients' own cells, their immune systems do not reject them as they might with organs transplanted from other donors.

Atala says his procedure did not replace the complete bladder in each patient, but a part of only the biggest, most bulbous portion of it excluding the neck.

ATALA: "If you can picture a light bulb, we would be replacing only a segment of the round portion."

In a Lancet commentary, physician Steve Chung of the Advanced Urology Institute of Illinois praises the work as a milestone, but says engineered bladders will not replace the grafts of intestinal tissue until further studies with longer follow-up confirm these first results. He foresees the day when the technique could replace cancerous bladders.

Dr. Atala says his laboratory at Wake Forest University is studying the procedures for growing new bladders for possible use with other internal organs.

ATALA: "Currently we are working on several other projects, including regeneration of cardiac muscle, liver, pancreas, nerve, kidney, blood vessels."

A U.S. company formed to market the bladder construction technique, Tengion, plans to apply later this year for U.S. government approval for larger clinical tests. David McAlary, VOA News, Washington.

The World Health Organization says a shortage of healthcare workers in poor countries is having a deadly impact. In its annual report, the WHO says too few doctors and other health workers are being trained, and WHO official Timothy Evans says many who are trained are leaving for jobs in richer countries, where demand — and pay — is high.

EVANS: "This growth of health systems and demand for health workers is pulling large numbers of skilled professional from developing countries, the so-called 'brain drain.' Twenty-five percent, or nearly 25 percent of doctors trained in Africa are currently working in OECD countries."

The World Health Organization says the problem is most acute in sub-Saharan Africa.

In a separate report issued this week, public health experts unveiled a blueprint for getting the maximum value out of scarce health care resources. They studied the world's leading causes of death and disability, and the least expensive ways to prevent or treat them.

Even wealthy countries have to make tough decisions about how best to allocate health care budgets. For poorer countries, the issue is much more urgent, and making the wrong decision can cost lives. Countries in sub-Saharan Africa typically spend $100 or less per person each year on health care.

Anthony Measham of the U.S. National Institutes of Health is co-editor of the report, called "Disease Control Priorities in Developing Countries." He told VOA that some of the best investments are in preventing disease.

MEASHAM: "One of the very biggest is to curb smoking. This has an enormous impact on heart attacks and stroke, as well as cancer of the lung and various other cancers. So one of the biggest recommendations of our work is to tax tobacco and to ban tobacco advertising."

Another big killer is HIV/AIDS. Treating the disease is expensive, so Measham said it's more cost-effective to focus on prevention.

MEASHAM: "One of the things we're recommending is 100 percent condom use, especially among populations at highest risk. That is extremely cost-effective, according to the evidence."

Anthony Measham says other inexpensive interventions with a big payoff include providing vitamin A, iron and iodine supplements to pregnant women; and using insecticide-treated bed nets, spraying to control mosquitos, and providing the best new drugs to prevent malaria.

More than 350 experts contributed to the report, which has the backing of the United Nations, the World Bank, and other development and health organizations.

Some of the recommended approaches aren't really medical at all. Speed bumps and other traffic-calming measures can have a dramatic impact, especially in countries where improving standards of living put inexperienced drivers behind the wheel of cars they never could afford before. A $5 investment can save a life or prevent costly, disabling injuries.

Allocating health resources is important even in the richest countries.

The United States spends more than any other country on health care, and both industry leaders and patients often say we Americans have the best health care in the world.

But despite that prevailing view, other Americans — including many doctors — question a system that permits an infant mortality rate about the same as Poland's, and produces a life expectancy no better than Cuba's — but at a much higher cost per person.

A new report issued this week highlights some of the discrepancies.

DAVIS: "What is disturbing about these findings is that while the U.S. ranks first on health care spending in the world, we are often last in measures of quality of care. Higher spending doesn't mean that we receive more or better care; we simply pay more."

Karen Davis heads the Commonwealth Fund, a foundation that supports research on health care. In a survey of patients in the United States and other wealthy democracies, the Americans scored their system lowest overall. They gave high marks to American medicine for preventive care, but low marks for safety, access to care, and equality of care:

DAVIS: "These shortfalls are a result of our fragmented system of care in the U.S., a system that is weak on primary care. In other countries they invest more in primary care and less in specialist care, perhaps gaining more value per dollar spent."

In some areas, the United States does very well. For example, almost all women [85%] now get mammograms to screen for breast cancer. In other areas, though, the picture is bleaker. Commonwealth Fund official Cathy Schoen says the survey found that about half of all Americans didn't see a doctor or take medicine because of the cost:

SCHOEN: "On 21 of the 30 indicators we found wide and statistically-significant differences in the U.S. by income. In other countries, differences by income were rare. Commenting on the report, Professor Donald Berwick of the Harvard University School of Public Health said the six-nation comparison highlights shortcomings in the way Americans get their health care.

BERWICK: "The fundamental conclusion from this report is that the U.S. is far from the best-performing health care system in the world, even though it's by far the most expensive. Except in preventive services, we lag signIficantly behind these other nations studied, and especially for people of low income and uninsured. We have the largest gap in care for the uninsured."

Andrew Bindman of the University of California–San Francisco says one fault in the U.S. system is that the tremendous resources that have gone into expensive, high-tech medicine have sometimes come at the expense of primary care, the regular doctor or clinic who first sees a patient.

BINDMAN: "We're seeing, for example, a decline in the numbers of individuals from U.S. medical schools, for example, going into primary care fields. We're seeing an erosion of the primary care practice and infrastructure that I think is contributing to some of the feelings of fragmentation that are also reinforced systemwide by the challenges people face with regard to health insurance.

It's important to note that this report was based not on measurable outcomes, such as infant mortality, but rather on how patients themselves assessed their satisfaction with the health care they receive.

Time again for our Website of the Week. You know, with studios in DC, surrounded by federal agencies like the HHS and NASA, riding to work in WMATA trains or driving in our SUVs, it's not surprising that at VOA we use a lot of abbreviations. We try to explain them, but it's easy to get lost in the alphabet soup. So sometimes we have to turn to Mike Malloy's website.

MALLOY: "Acronym Finder is the web's largest searchable database of acronyms and abbreviations from all subject areas."

Despite the name, AcronymFinder.com includes both acronyms and abbreviations, which are often confused. An acronym is an abbreviation that is pronounced as a word. For example, AIDS, which is pronounced as a word, is an acronym; but HIV, which is letter-by-letter, is just a plain abbreviation.

The site is advertiser-supported, and sometimes the screen can get a bit cluttered, but it's all text.

MALLOY: "There aren't a lot of graphics. We don't have pop-up advertising or anything like that. I think users would find the site to be very fast, even on a dial-up connection."

Malloy started collecting acronyms when he was working for the government, which is a prime user — and creator — of them. He put his own list online about 10 years ago, and soon others wanted to contribute.

MALLOY: "So I created a facility that allowed users to submit new submissions to the site and, believe it or not, we add about 200 new definitions every single day."

To ensure accuracy, those submissions are verified by an actual human editor.

Although Acronym Finder has its roots in military and government terms, the website is now also full of terms from the Internet, pop culture, music, games and technology — ROTF, NIN, GTA* and so on. Most of the terms are in English, but Mike Malloy says there are about 5,000 acronyms and abbreviations in other languages, too.

So if you're looking for abbreviations and acronyms, find them ASAP, online at AcronymFinder.com, or get the link from our site, VOANews.com/ourworld.

Some of the biggest U.S. film studios this week began offering an Internet service allowing users to download movies and watch them on their computers. The new service competes with other movie sources, both legal and, shall we say, unauthorized. Alan Silverman reports from Hollywood that the new service has built-in limitations as the studios walk the thin line between protecting their product and competing with new technologies.

CLIP FROM "BROKEBACK MOUNTAIN" "I wish I knew how to quit you."

SILVERMAN: At the same time that "Brokeback Mountain" hits video store shelves, savvy computer users can download the entire movie ... legally. The Oscar-winning drama is the inaugural release of a new video-on-demand service from Movielink. Five of the major Hollywood studios started the California-based company four years ago to offer time-limited online rentals of feature films; but Movielink chief executive officer Jim Ramo says purchasers can now own a downloaded digital copy to watch over and over again:

RAMO: "What we've tried to do with our launch is to have a great mix of Academy Award winners, blockbusters and classics."

SILVERMAN: Warner Brothers Home Entertainment president Kevin Tsujihara says the new plan provides a legal alternative to online theft estimated to cost the entertainment industry more than $4 billion annually:

TSUJIHARA: "Obviously it's a factor in the decision-making. Consumers are telling us through the usage patterns that we're seeing from piracy that they're looking for our content in this form. It's one thing for people to do it when it's free. It's another when we're asking them to pay for that content, but obviously there is a demand and a usage that's being done."

SILVERMAN: Movielink CEO Ramo says the company's experience with some 100,000 rental downloads per month demonstrates that illegal copying can be prevented:

RAMO: "All of our content is secured with a digital rights management system. What that means is encryption of the movie file so it is very, very difficult to de-crypt. And

SILVERMAN: Will it replace DVDs that currently bring the studios $40 billion in annual worldwide sales? Movielink CEO Tom Ramo believes it is too soon to tell. For now, he says film fans should consider download-to-own another option: one that is higher quality and safer than illegal, pirate copies. Alan Silverman for the Voice of America in Hollywood.

In Africa, one in three people is undernourished. One reason: the amount of productive farmland is rapidly diminishing, due to poor soil management and the lack of fertilizer. If unchecked, experts say the trend will worsen the continent's food shortage. VOA's Adam Phillips reports on the announcement in New York of a multi-billion dollar effort to launch a green revolution in Africa.

OBASANJO: "Put simply: our quest is to nourish Africa's soil and the feed the continent."

PHILLIPS: The simple goal articulated by Nigeria's president, Olusegun Obasanjo, represents a daunting challenge. Africa's farms are extremely unproductive compared to most of the rest of the world. One important reason for this is the state of its overworked soil, which has been drained of the nutrients that plants need to grow. Most experts agree that more fertilizer, more widely used, is a key to solving the problem.

African farmers, on average, apply less than 10 kilograms of organic and chemical fertilizer per hectare on their crops — less than one tenth the world average. Without enough nutrients, harvests decline. So African farmers try to boost yields by expanding into the forests beyond their farms.

ROY: "They are moving to new land, cutting down the trees and then burning them.

PHILLIPS: That's a temporary solution, says Amit Roy, president of the International Center for Soil Fertility and Agricultural Development.

ROY: "And then the ash from the trees has nutrients which fertilize the soil, they grow crops out of it for a couple of years, extract the nutrients out of it and then it becomes dead! The soil becomes absolutely unproductive. Then the farmers move into another area."

PHILLIPS: Once, Africa's population was small enough, and the land vast enough, to tolerate this practice. However, Africa's population is exploding, while the amount of arable land has declined. As farmers penetrate deeper and deeper into virgin forest, erosion problems worsen, and ever greater swaths of land are destroyed.

ROY: "…And if we continue to do it this way, you are reaching a point where the entire African biodiversity and wildlife population is going to be threatened. It already has started. So our idea is to make the existing agricultural land more productive through better management of nutrients — which is both fertilizer [and] organic matter, so that the farmers are able to productively grow but essentially grow from the same land and then we worked with them to market excess and sell their produce and get some imcome out of it."

PHILLIPS: Amit Roy's organization, IFDC, has just released a major report on Africa's soil crisis. Later this year, after an African Union fertilizer summit, steps will also be taken to lower Africa's fertilizer costs -- now four to six times the world average — and create incentives for vastly increased fertilizer production within Africa. But President Obasanjo of Nigeria, who will host the summit, says adding fertilizer alone is not enough.

OBASANJO: "We must use the right types of fertilizers in a judicious and environmentally sound manner and improve farmers' knowledge on efficient use, and encourage safe storage and handling and avoid overuse. We must also pay attention to water issues, especially water harvesting and extension and expansion of irrigation."

PHILLIPS: Guy Alpha Oumar Konaré, Chairman of the African Union Commission, said through a translator that this will help catalyze Africa's own "Green Revolution."

KONARÉ: "Without a green revolution we will simply remain in the logic of food aid which will never, never end food insecurity. Without a green revolution, we will never be bale to create resources and reduce poverty. Without a green revolution we will never be able to have real control on our environment."

PHILLIPS: The Africa Fertilizer Summit is scheduled for June in Abuja, Nigeria. For Our World, I'm Adam Phillips reporting from New York.

MUSIC: "Our World" theme

That's our show for this week. Drop us a line, let us know what you think. We're always happy to hear from you. If you've got a science question and we answer it on the air, we'll send you a special VOA gift as our way of saying thanks. The email is ourworld@voanews.com. Or use our postal address —

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The show was edited by Rob Sivak. Eva Nenicka is our technical director. And this is Art Chimes, inviting you to join us online at voanews.com/ourworld or on your radio next Saturday and Sunday as we check out the latest in science and technology...in Our World.